In a recent study aimed at exploring the effects of sardine protein on insulin resistance, two different groups of rats were fed diets of either protein from sardines or from casein. Rats from both groups were also fed a high fructose (fruit sugar) diet for 2 months. Rats fed the high fructose diet were found to have greater body weight, more fatty tissue and lower food intake compared to control rats. An increase in blood glucose, insulin, triglycerides (fats) and free fatty acids, as well as an impaired glucose tolerance and insulin resistance was observed in high fructose fed rats. There was also a loss of antioxidants such as vitamin E and beta-carotene; important for protection against coronary heart disease and a rise in lipid peroxidation; the process in which free radicals steal electrons from the lipids (fats) in cell membranes, resulting in cell damage.
Rats fed the sardine protein diet exhibited lower food intake and fat mass than those fed casein protein diets. Sardine protein diets reduced levels of insulin in the blood and insulin resistance, blood triglycerides and free fatty acids were also lowered. The sardine protein diet significantly decreased blood glucose levels in subjects being fed high fructose. The results for rats being fed a casein protein diet were nowhere near as beneficial as those on the sardine protein diet.
Sardine protein consumption lowered hydrogen peroxide levels in fat around the kidneys and in brown fat (a type of fat in the body which is used to generate heat). Hydrogen peroxide is toxic to cells in the body and it is important to keep levels at a minimum; a decrease in these levels means enhanced activity of antioxidant enzymes. Sardine protein diets also prevented hyperleptinemia and reduced inflammatory status in comparison with rats fed the casein diet. Hyperleptinemia is where a person becomes resistant to the effects of leptin, in the same way a person with type 2 diabetes is resistant to the effects of insulin. Leptin is a protein hormone that plays a key role in regulating energy intake and expenditure, therefore reducing appetite.
The end results of the study show the beneficial effects that sardines have in a diet that is high in fructose (the sugar found in fruit); by reducing the chances and even protecting against associated diseases such as insulin resistance, hyperleptinemia and hyperglycaemia.
One can of sardines provides approx. 22.6g of protein and 191 calories, with 90.6 of those calories coming from the protein. Sardines are also a rich source of omega-3, vitamin D, calcium and vitamin B12. They are non-predatory fish, which means they are very low in contaminants such as mercury.